paul-loedige
58 lines
1.8 KiB
Markdown
58 lines
1.8 KiB
Markdown
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date = '2022-09-04T15:43:06'
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draft = false
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title = 'Regex Basics'
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type = 'post'
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tags = ['Misc']
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[just text:](#just-text) matches any string with the given text inside it
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[^](#^) matches string that starts with the given text
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[$](#$) matches string that ends with the given text
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[*](#*) zero or more
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[+](#+) one or more
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[?](#?) zero or one
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[{n}](#{n}) `n` occurrences
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[a|b or [ab]](#OR-operator) a or b
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[\\d](#\\d) matches a digit
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[\\w](#\\w) matches a word character (alphanumeric plus underscore)
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[\\s](#\\s) matches a whitespace character
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[.](#.) matches any character
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## Anchors
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### just text
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`abc` matches any string that has the text _abc_ in it
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### ^
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`^abc` matches any string that starts with _abc_
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### $
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`abc$` matches any string that ends with _abc_
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### exact match
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`^abc$` matches only the exact string _abc_
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## Quantifiers
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### *
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`abc*` matches any string containing _ab_ followed by any number of _c_ s
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### +
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`abc+` matches any string containing _ab_ followed by at least one _c_
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### ?
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`abc?` matches any string containing _ab_ followed by at the most one _c_
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### {n}
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`abc{2}` matches any string containing _ab_ followed by two _c_ s
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`abc{2,}` matches any string containing _ab_ followed by two __or more__ _c_ s
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`abc{2,5}` matches any string containing _ab_ followed by between two and five _c_ s
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## OR operator
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`a|b` _a_ or _b_
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`[abc]` _a_ or _b_ or _c_
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## Character classes
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### \d
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`\d` matches any character in a string that is a digit
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`\D` matches any character that __isn't__ a digit
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### \w
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`\w` matches any character in a string that is a word character
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`\W` matches any character that __isn't__ a word character
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### \s
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`\s` matches any whitespace character in a string
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`\S` matches any __non__-whitespace character
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### .
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`.` matches any character in a string |